Activate item shop:
Highlight the "Buy Item" option before a battle and press Y, A, Down, X, B. A sound will confirm correct code entry.

Level select:
Press L, Y, Right, R(2), A + Start at the starting menu. To play any level already completed, press L, Y, R(2), A at the starting menu.

Sound test:
Press A, Z, Y, X, A, Z, X, Y at the starting menu.

Unlimited money:
Purchase and collect items until a second page is displayed in the inventory. Remove all weapons and fill the second inventory page. Begin selling items starting at the last position on the second page. At some point the game will allow the same item to be sold multiple times. Continue selling this item to build your total funds.